In a portable medium such as an IC card, as shown in FIGS. 1 and 2, a semiconductor chip constituting an unillustrated microcomputer and a memory is embedded in a pocket sized card base material 1 made of plastic, etc. A plurality of external terminals are disposed on a surface of the card base material to transmit and receive data between the card and an external apparatus such as a reader, writer, etc., and to input a power source to the card, for example.
In accordance with the rules of the International Standard Organization, the thickness of the card base material 1 must be 0.76 mm, and have predetermined longitudinal and transversal lengths.
Further, the IC card is constructed to be used together with a known magnetic card including a magnetic stripe 3 and embossed characters 4 on the surfaces of the card base material 1.
FIG. 3 shows a conventional method for manufacturing embossed characters, etc., in the card base material 1 of such an IC card.
In FIG. 3, a female die 6 is arranged on the front surface side of the card base material 1, and the card base material 1 is pressed by a male die 5 upwards from the back face side of the card, thereby manufacturing required embossed characters 4 on the surface of the card base material 1.
As shown in FIG. 4, a new IC card has recently been considered in which a keyboard 7 and a liquid crystal display section 8 are disposed on the back face of the card base material 1 and the content of a memory is confirmed by operating a microcomputer disposed in the card by manual operation without using a reader, a writer, etc.
However, in such IC card in which the keyboard 7, etc. are disposed on the back face, when the male die 5 is pressed on the back face side of the card, the keyboard 7 may be damaged. Thus, the embossed characters cannot be formed on the surface of the card by pressing the card base material 1 upwards from the back face side by the male die 5 when such instruments as keyboards and LCDs are included.